Success with corn all in the details

Trying to harvest corn on 38-inch row spacings with a 30-inch corn header may be like trying to pick cotton on 30-inch row spacings with a conventional picker. It might work, but the results may not be all that satisfactory.

To veteran corn producers, the idea of matching row spacings and corn headers may sound rather elementary. But for first-time corn growers who are more accustomed to harvesting soybeans and wheat, the fact that corn headers come in different row widths may be a surprise.

“One thing new corn growers in the South might want to check is the row widths on their corn headers,” says Bill Wiebold, Extension corn and soybean specialist with the University of Missouri-Columbia. “Most of the world has moved to 30-inch rows in corn, but I know cotton traditionally has been planted on 38-inch rows.”

That was one of several topics Wiebold talked about in a wide-ranging discussion on the potential shift in acres from cotton, soybeans and rice to corn not only in the Mid-South and Southeast but also in the Midwest.

Some of that shifting — the University of Missouri's Food and Agricultural Policy Research Institute has been predicting another 8.3 million acres of corn could be planted in 2007 — may have been short-circuited by the unusually dry conditions in the Mid-South in mid- to late March.

Wiebold said numerous reports of Mid-South growers trading cotton pickers in on combines and corn headers and building storage bins indicates the shift to corn may be of a more permanent nature than some observers have indicated.

“If farmers are trading equipment for combines, that may be a signal this change may be longer term than we thought,” he said in an interview in his office on the University of Missouri campus.

Missouri, which has been more of a soybean state than its neighbors to the north and east, is expected to move some acres to corn, but not on the percentage scale that had been predicted for the Mid-South and Southeast.

“We normally have about 5 million acres of soybeans in Missouri,” he said. “I'm guessing we might drop to 4.5 million with most of the difference being added to the 3 million acres of corn we typically grow. But even a 10 percent change would be pretty dramatic.

“I know some people are kind of testing the idea of growing more corn because of the higher prices, but some of our soils and weather are just better suited for soybeans. And soybean prices are also up, which will hold some of those acres.”

Producers can experience harvesting losses of 2.5 bushels per acre if the gathering opening is 4 or 5 inches off the row, according to University of Arkansas Extension specialists. (Corn headers are designed so that stalks are pulled into the relatively narrow gathering opening and the ears stripped off the stalk.)

If damage from windstorms or corn borers cause ears in misaligned rows to drop off, Arkansas specialists say, field losses can exceed 10 bushels per acre.

“The vast majority of corn growers are set up for 30-inch rows because of the increased yield potential,” says Wiebold. “So you're more likely to find 30-inch row corn headers unless you run across an older model header. I know some of the equipment at the Delta Research Center at Portageville has been set up on 38-inch rows for cotton.”

Timely harvesting will also be important in the South because of the potential for high winds from hurricanes and for the development of aflatoxin when weather conditions turn dry.

Corn harvested between 19 and 24 percent moisture normally has minimal kernel damage, according to research. Preharvest and gathering losses can vary with insect damage, lodging and how tightly ears are held.

Arkansas Extension specialists say aflatoxin isn't likely to be a problem in well-managed corn. “However, aflatoxin proliferates so rapidly in Mid-South fields that a grower should consider his options,” they say. “If corn can be dried to 15 percent or below within a day, the spread of aflatoxin is minimized by early harvest.”

Wiebold says growers may have other considerations, depending on the marketing outlets available. “I'm not sure about where the corn in the South is going, but an ethanol plant will reject corn with aflatoxin faster than a grain elevator.”

Corn destined for dairy cattle can be rejected for as low as 5 parts per billion of aflatoxin, a naturally occurring toxin produced from metabolites of the aspergillus species fungus. Ethanol plants generally apply the same or stricter standards because “the manufacturing process just concentrates the aflatoxin in the dry distillers grain.”

If corn is being discounted for aflatoxin in their region this summer, growers may want to take precautions, such as harvesting the “corners” outside their center pivots separately from the remainder of the field since drought-stressed corn is more likely to contain aflatoxin.

“It would be terrible to increase the amount of corn in an area tenfold and then not have anywhere to go with it,” says Wiebold. “In general, the faster you can dry it to 10 percent to 15 percent moisture, the less likely the corn will be discounted for aflatoxin.”

The Missouri specialist says he believes corn can be a good crop for the Mid-South. “Growers in the Mid-South have good river transportation,” he said. “They're not as concerned about the barge basis as farmers in the Midwest where we simply don't have enough.”

And corn being planted on fields where it hasn't been grown in a while can be a good thing. “Corn going into ground where there hasn't been any corn generally gets a little bump on yield,” Wiebold notes. “In the Midwest, we're seeing a 10 percent to 12 percent depression in yields when we follow corn with corn.”

Growers in all corn-growing regions are being advised to line up supplies of nitrogen and atrazine herbicide formulations in advance because of potential shortages due to increased corn acres in some areas.

Pest problems can also be more of a concern in the Mid-South and Southeast, especially since southern corn producers have a 50 percent refuge requirement for Bt hybrids in cotton-growing regions compared to 20 percent in the Midwest.

“When you think insects, think scouting whether you're growing a Bt hybrid or not,” he said. “Some of the insects, such as the corn earworm (bollworm), will be familiar to cotton growers. But other pests may have to be identified since producers may not be accustomed to seeing them.”

Corn diseases also bear watching, depending on weather conditions. “You get that much corn, some diseases may take off a bit.”

He also recommends growers pay close attention to the water needs of the corn plant. “The most critical time appears to be two weeks ahead of silking and two weeks after. You can lose 40 percent of your yield due to stress then.”

If a grower needs help with irrigation scheduling, most states now have Web- or Internet-based irrigation planner programs that can help them decide when to water each of their crops. “Corn needs water and can need watering fairly often,” says Wiebold. “That's why it should be planted early in the South — to get to the silking stage when rainfall is normally more abundant.”

He said the new interest in corn makes it fun to be an agronomist. “Good farmers will learn the basics fast. It will be interesting to see how all this new interest in the crop turns out.”